Mechanical and electronic devices help in locomotion and prehension functions, and in the rehabilitation process. Hybrid orthoses are wearable devices equipped with more than one mobility technology. Monitoring joint angles is required for indoor and outdoor applications. In the latter scenario, this monitoring can be a hard task. This article describes the development and implementation of a biomedical portable instrumentation for angular monitoring of lower limbs for rehabilitation purposes, using IMUs, ESP32, and ESP-NOW protocol. The modular system consists of two modules: measurement and processing. In the former, sensors are positioned on adjacent limbs to measure angles in between. In the later, ESP32 processes and sends data to a gateway via ESP-NOW, which makes it available on a web page. The solution has a safe 10 h autonomy. Results showed the devices’ successful implementation, calculating angles (linear regression, R2 = 1, 1,01° error, Sy.x = 0,2012), sending them (transmission delay 15 ms; 65 samples/s), and visualizing limb angles on a web page separately (32B storage per sensor pair), displaying both absolute and relative ranges of movement.